Solved: Water-Damaged iPhone 6S stuck on White Apple Logo after booting

The iPhone 6S fell into water, and then it stuck on white Apple logo after booting. It was repaired once before, when we received it, the iPhone 6S in white Apple status and it will be restarted occasionally. After remove the iPhone logic board, we found that the iPhone U2 IC and charge tube has been replaced.

Check the iPhone logic board under a 3.5X-90X Stereo Zoom Microscope 14MP HDMI Camera, there are small beads around the chip, which is a serious mistake. Clean up the iPhone logic board and then replace the new U2 IC and charge tube, but the problem still the same, iPhone stuck on white Apple logo and restart occasionally.

Use Fluke 15B+ Digital Multimeter to measure the diode data for iPhone battery detective pin, the data is normal, the resistance of iPhone booting condition is normal, and the voltage also is normal.

For the watered-iPhone, iPhone system is less damaged. After consulting with the customer, we start to flash iPhone. Connect iPhone to computer with iPhone lightning cable, the computer pop-up prompts that USB is not recognized. We suspect that the problem will be in the U2 circuit line. Take off the U2 to measure the resistance value.

After measurement, the U2 IC F4 pin PP3.0V_TRISTAR is short circuit, this point is connected to power and an inductor FL5408_RF next to an iPhone WIFI module IC, the U5411_RF receive amplifier is connected to the head of iPhone logic board. In order to find the problem point correctly, first we remove the FL5408_RF, measuring the ends of the inductor, we found a short circuit at the end of the amplifier.

 

Remove the two capacitors on the bottom, the problem still there. Remove the U5411 IC, and then measure it, the data is normal. The glue around this chip is very soft，use QUICK 861DW hot air rework station in 150 degree to remove it is enough, and please don't remove the capacitor next to it.

Finally, install the IC, re-weld the FL5408_RF, test iPhone and it can be turned on properly.

Detailed Solution for iPhone 6 won't boot after dropped into water (short-circuit)

If the iPhone dropped into water, then you must have the idea that the iPhone motherboard is damaged.  Moreover, the iPhone won't boot. After water damaged, the most common phenomenon is the short circuit on the motherboard, and there has two cases. Let's take iPhone 6 won't boot after dropped into water as the  an example.

 

The water damaged the iPhone 6, now the problem is that the iPhone 6 won't boot.

First of all, we need to disassemble the iPhone, take off the iPhone motherboard, and then measure it with DC power supply.

Case 1

When supply power to measure the iPhone motherboard, there is large current alerts on DC power supply display screen, which means that there is a leakage phenomenon. Generally, when powering the motherboard and then it shows power leakage issue, the Rosin method is the best choice.

Use Fluke 15B+Digital Multimeter to measure the diode data for iPhone battery interface positive, the data is normal. Continue to measure the diode data for main power supply VCC_MAIN circuit, finding that the diode data for this circuit line is too small, which means that there is a short circuit here.

Smoke the iPhone motherboard to white with rosin, add voltage on VCC_MAIN, after for a while, we found a capacitor is shorted.

With the help of QUICK 861DW rework station and tweezers, we remove it smoothly and quickly. After remove that capacitor, measure it again, the data is normal now.

Install the iPhone to test, the iPhone 6 can be turned on smoothly.

Case 2

When the iPhone motherboard is being measured by powering, it won't leak, but when we press the iPhone power button, the current stuck on 200mA. Obviously, a load on the iPhone power IC is short-circuited.

Use multimeter to measure the resistance of each output grounded on the iPhone power IC, when the PP1V8_SDRAM circuit is measured, we found the problem, the PP1V8_SDRAM circuit is shorted, because the data for C1243 is too small.

Put iPhone motherboard under the Phone Repair 7-45X Trinocular Stereo Microscope, and then apply some rosin on motherboard, and then use Quick 861DW hot air rework station to smoke it, till the motherboard turns white.  Increase the voltage in the C1243, after a while, we found a capacitor is shorted.

Remove this capacitor as usual, and then measure it again, now the data is normal.

Assemble the iPhone to test; now the iPhone 6 can be turned on smoothly. After get into IOS, test all function on iPhone, everything works well.